A light-emitting diode (referred to as “LED” in the following) is known as a light-emitting element including a semiconductor multilayer film. In particular, when a LED for emitting blue light such as a GaN LED is combined with a phosphor that emits yellow light by excitation of the blue light, the LED can be applied to a light-emitting device for emitting white light (e.g., JP 2001-15817 A).
FIGS. 12A and 12B show a conventional light-emitting device. FIG. 12A is a schematic top view of the light-emitting device, and FIG. 12B is a cross-sectional view taken along the line I-I in FIG. 12A.
As shown in FIGS. 12A and 12B, a light-emitting device 100 includes a substrate 101, a conductor pattern 102 that is formed on the substrate 101, a LED chip 103 that is flip-chip mounted on the conductor pattern 102, and a phosphor layer 104 that is formed to cover the LED chip 103.
As shown in FIG. 12B, the LED chip 103 includes a sapphire substrate 110 and an n-type semiconductor layer 111, a light-emitting layer 112, and a p-type semiconductor layer 113 that are formed in this order on the sapphire substrate 110. The light-emitting layer 112 is not in contact with a portion 111a of the principle surface of the n-type semiconductor layer 111 that faces the substrate 101, and the portion 111a is provided with an n-side electrode 114a. The n-type semiconductor layer 111 is connected electrically to the conductor pattern 102 via the n-side electrode 114a and a gold bump 115. The p-type semiconductor layer 113 is connected electrically to the conductor pattern 102 via a p-side electrode 114b and a gold bump 115.
When light is produced by the light-emitting device 100 with this configuration, the light emitted from a region of the phosphor layer 104 that is located directly above the portion 111a of the principal surface of the n-type semiconductor layer 111 is not white, but yellow. This is because the optical path length of blue light passing through the phosphor layer 104 located directly above the portion 111a becomes longer, and the phosphor is likely to be excited by the blue light, thus increasing a yellow light component generated from this region. During the emission of light, as shown in FIG. 12A, the upper surface of the phosphor layer 104 includes a region 104a (with hatching) that is located directly above the portion 111a and emits yellow light and a region 104b (without hatching) that emits white light. Thus, the luminescent color of the light-emitting device 100 is not uniform, which can make it difficult to use the device in a lighting unit or a display unit.